1. Field of Invention
This invention relates to a grommet, and more particularly to a grommet which enables an elongate member (e.g. a wire harness) to be positively and easily passed through and held on a mounting plate such as a vehicle body panel.
2. Related Art
There have heretofore been proposed various grommets for mounting a wire harness on a vehicle body panel of an automobile in such a manner that the wire harness passes through the vehicle body panel.
In a conventional art of JP-A-8-212857, a grommet includes a smaller-diameter tubular portion for fitting on a wire harness, a larger-diameter tubular portion for fitting in a mounting hole in a vehicle body panel, a tapering tubular portion interconnecting the smaller-diameter tubular portion and the larger-diameter tubular portion, a fitting groove formed in an outer peripheral surface of the larger-diameter tubular portion, and holding piece portions formed on the outer peripheral surface of the larger-diameter tubular portion.
In this conventional construction, first, the wire harness is fitted in the smaller-diameter tubular portion, and in this condition that portion of the grommet, including the tapering tubular portion and the larger-diameter portion, is reversed or turned (in one longitudinal direction) inside out at a smaller-diameter end of the tapering tubular portion, and is fitted on the smaller-diameter tubular portion, so that the holding piece portions are disposed radially inwardly of the fitting groove.
Then, the wire harness is pushed to be passed through the mounting hole in the panel, so that distal end portions of the holding piece portions are inserted into the mounting hole in the panel, with the reversed larger-diameter tubular portion held against a surface of that portion of the panel disposed around the peripheral edge of the mounting hole. Then, the wire harness is further pushed in the one direction so as to cause the grommet to produce its own restoring force, so that the tapering tubular portion and the larger-diameter tubular portion are restored into their respective initial shapes, and at the same time the fitting groove is fitted on the peripheral edge of the mounting hole.
Further, in this conventional construction, the wire harness can be mounted in the mounting hole in a panel according to the following procedure. First, the smaller-diameter tubular portion is fitted on the outer periphery of the wire harness, and in this condition that portion of the grommet, including the tapering tubular portion and the larger-diameter portion, is reversed or turned (in one longitudinal direction of the wire harness) inside out, and is fitted on the smaller-diameter tubular portion, so that the holding piece portions are disposed radially inwardly of the fitting groove, and also the fitting groove and the holding piece portions are directed toward one side portion of the wire harness. Then, that portion of the wire harness, extending from the grommet in the one direction, is passed through the mounting hole in the panel, and is pulled, thereby inserting the distal end portions of the holding piece portions into the mounting hole, so that the reversed larger-diameter tubular portion is abutted against a surface of that portion of the panel disposed around the peripheral edge of the mounting hole. Then, the wire harness is further pulled in the one direction so as to cause the grommet to produce its own restoring force, so that the tapering tubular portion and the larger-diameter tubular portion are restored into their respective proper initial shapes, and at the same time the holding piece portions are turned in sliding contact with the peripheral edge of the mounting hole, so that the fitting groove is fitted on the peripheral edge of the mounting hole by this guiding action of the holding piece portions. Therefore, the wire harness can be easily and positively mounted in the mounting hole through the grommet with a small force.
In the above conventional construction, the reversed portion must be restored into the initial shape by further pushing the wire harness through the mounting hole until the restoring force is produced after the larger-diameter portion abuts against the panel surface.
In the above conventional construction, however, the tapering tubular portion and the larger-diameter tubular portion are turned inside out at the smaller-diameter end (i.e., proximal end) of the tapering tubular portion, and therefore there has been encountered a problem that the restoring action into the initial shape is large, so that it is difficult to smoothly fit the grommet in the mounting hole.
With respect to grommets of the ordinary type which are not reversed before mounting on the panel, there have been proposed the type of grommets having additional passage hole or holes for passing cables or hoses other than a wire harness.
With respect to the grommet of the above-mentioned type designed to be reversed before mounting on the panel, the larger-diameter portion is reversed, and therefore there has not heretofore been provided such grommet capable of passing a cable, a hose or the like in addition to the wire harness.
This invention has been made in view of the above problem, and an object of the invention is to provide a grommet which enables an elongate member (e.g. a wire harness) to be easily and positively mounted on a mounting plate, such as a vehicle body panel, in such a manner that the elongate member passes through the mounting plate.
Another object of the invention is to provide a reversal-type grommet capable of additionally passing a cable, a hose or the like other than a wire harness.
The above object has been achieved by a grommet for enabling an elongate member to be passed through and held relative to a mounting hole formed in a mounting plate, including a first cylindrical portion for passing the elongate member therethrough, a generally-conical, annular connecting portion formed on an outer peripheral surface of the first cylindrical portion, a second cylindrical portion connected to the first cylindrical portion through the connecting portion, a groove formed in an outer peripheral surface of the second cylindrical portion, and a flange portion formed on that portion of the outer peripheral surface of the second cylindrical portion lying between the groove and the connecting portion; wherein the second cylindrical portion is turned inside out, with an inner peripheral surface thereof exposed outwardly, and a peripheral edge of the flange portion is inserted into the mounting hole, and subsequently the second cylindrical portion is restored into its initial shape, thereby passing the first cylindrical portion through the mounting hole, and also fitting the groove on a peripheral edge of the mounting hole; provided in that a rib is formed along a generatrix of the connecting portion, and extends continuously from a smaller-diameter end of the connecting portion toward a larger-diameter end thereof to a predetermined position.
The first cylindrical portion has the inner diameter corresponding to the outer diameter of the elongate member (such as a wire harness), or may have the slightly-smaller inner diameter so that the elongate member can be press-fitted into the first cylindrical portion. This first cylindrical portion does not need to have the uniform inner diameter or the uniform outer diameter throughout the length thereof, but may have a stepped cylindrical shape or a tapering cylindrical shape.
The second cylindrical portion has the outer diameter corresponding to the inner diameter of the mounting hole, and is connected at its proximal end to the peripheral edge of the connecting portion.
Therefore, the first and second cylindrical portions may be arranged, for example, in a telescopic manner, or may be connected together along the axis through the connecting portion.
The first cylindrical portion, the connecting portion and the second cylindrical portion may be formed integrally with one another, using a synthetic resin having suitable elasticity and water-resistance. However, these portions may be separate in so far as the second cylindrical portion has suitable elasticity and water-resistance.
The flange portion may comprise an annular flange formed continuously on the outer peripheral surface of the second cylindrical portion over the entire circumference thereof, or may comprise a plurality of flange portions formed at predetermined intervals in the circumferential direction.
The flange portion can be made larger in thickness than the second cylindrical portion, and can have a predetermined metal plate insert-molded therein.
The connecting portion has a generally conical, annular shape, and therefore the generatrix of the connecting portion means a line at which a plane, including the axis of the cone, intersects the conical surface. The rib is formed along this generatrix, and therefore the rib lies in the plane including the axis of the cone.
In the grommet of this construction, the rib extends continuously from the smaller-diameter end of the connecting portion toward the larger-diameter end thereof to the predetermined position, and therefore the position, at which the connecting portion is folded, is determined by this rib. Namely, the connecting portion is less liable to be folded at the region where the rib is provided, and when the second cylindrical portion is reversed or turned inside out, the connecting portion will not be folded at the proximal end thereof, but is folded at that portion thereof (intermediate the opposite ends thereof) near to the second cylindrical portion. Therefore, although the grommet is turned inside out over an area, including the second cylindrical portion and part of the connecting portion, the grommet is not turned inside out over an excessively-large area (that is, not reversed excessively), but is turned inside out over a smaller area, and is kept in a configuration analogous to the configuration which the grommet assumes immediately before the grommet begins to be restored into its initial shape by its own restoring force. Therefore, in the next step, when the second cylindrical portion is pressed against the panel surface, thereby imparting a restoring force to the grommet so as to restore the same into its initial shape, the restoration of the grommet can be immediately started, and therefore the fitting of the grommet can be effected smoothly.
Thus, the above-mentioned object is achieved.
The rib is formed respectively along the generatrix of the connecting portion, and therefore the connecting portion will be twisted even when a tensile force or a compressive force acts on the rib during the reversing operation.
In the present invention, the first cylindrical portion is disposed within the second cylindrical portion, and the rib is formed on an inner peripheral surface of the connecting portion, and is connected to the outer peripheral surface of the first cylindrical portion.
In this grommet, the rib extends between the inner peripheral surface of the connecting portion and the outer peripheral surface of the first cylindrical portion, and hence is not exposed to the exterior. Therefore, for example, when mounting the grommet in the mounting hole in the panel, the rib will not interfere with other portion, and hence will not hinder this operation. When the grommet is turned inside out, the position, at which the connecting portion is reversed or folded, is determined by the tension of the rib, and therefore the effect of determining the position of reversal or folding of the connecting portion can be fully achieved without the need for increasing the thickness of the rib.
Incidentally, even when the rib is formed on the outer peripheral surface of the connecting portion, the effect of determining the position of folding of the connecting portion by the rib can be achieved. In this case, however, the rib would be somewhat buckled by a compressive force unless the thickness of the rib is increased. Therefore, it is preferred that the rib be formed on the outer peripheral surface of the connecting portion as described above.
In the present invention, there are provided a plurality of ribs, and the plurality of ribs are arranged radially with respect to the axis of the connecting portion.
In this grommet, the plurality of ribs are arranged radially with respect to the axis of the connecting portion, and therefore when the grommet is turned inside out, the connecting portion can be folded or bent uniformly over the entire circumference thereof. Namely, the folded portion of the connecting portion can be disposed generally in a common plane, perpendicular to the axis thereof, over the entire circumference thereof. Therefore, the uniformly-reversed condition of the connecting portion can be achieved over the entire circumference thereof, and the whole of the reversed portion of the connecting portion 23 can be restored at a time over the entire circumference, thereby fitting the grommet into the mounting hole.
The above object has been achieved by a grommet for enabling an elongate member to be passed through and held relative to a mounting hole formed in a mounting plate, including a first cylindrical portion for passing the elongate member therethrough, a generally-conical connecting portion formed on an outer peripheral surface of the first cylindrical portion, a second cylindrical portion connected to the first cylindrical portion through the connecting portion, and a groove formed in an outer peripheral surface of the second cylindrical portion; wherein the second cylindrical portion is turned inside out, with an inner peripheral surface thereof exposed outwardly, and subsequently the second cylindrical portion is restored into its initial shape, thereby passing the first cylindrical portion through the mounting hole, and also fitting the groove on a peripheral edge of the mounting hole; provided in that there is provided a tubular passage portion which communicates the inside and outside of the connecting portion with each other, and projects outwardly from an outer peripheral surface of the connecting portion, and an axis of the passage portion extends along a generatrix of the outer periphery of the first cylindrical portion.
The first cylindrical portion has the inner diameter corresponding to the outer diameter of the elongate member (such as a wire harness), or may have the slightly-smaller inner diameter so that the elongate member can be press-fitted into the first cylindrical portion. This first cylindrical portion does not need to have the uniform inner diameter or the uniform outer diameter throughout the length thereof, but may have a stepped cylindrical shape or a tapering cylindrical shape.
The second cylindrical portion has the outer diameter corresponding to the inner diameter of the mounting hole, and is connected at its proximal end to the peripheral edge of the connecting portion.
Therefore, the first and second cylindrical portions may be arranged, for example, in a telescopic manner, or may be connected together along the axis through the connecting portion.
The first cylindrical portion, the connecting portion and the second cylindrical portion may be formed integrally with one another, using a synthetic resin having suitable elasticity and water-resistance. However, these portions may be separate in so far as the second cylindrical portion has suitable elasticity and water-resistance.
In the grommet of the invention, a flange portion may be formed on the second cylindrical portion. The flange portion may comprise an annular flange formed continuously on the outer peripheral surface of the second cylindrical portion over the entire circumference thereof, or may comprise a plurality of flange portions formed at predetermined intervals in the circumferential direction.
The flange portion can be made larger in thickness than the second cylindrical portion, and can have a predetermined metal plate insert-molded therein.
The passage portion can have a tubular shape of a desired cross-section having opposite open ends, or can have an end cap formed at a distal end thereof, so that it has a so-called closed-bottom tubular shape. In the case where the tubular passage portion has the end cap, the end cap is cut off or incised if necessary. A plurality of such passage portions may be provided.
The grommet of this construction has the tubular passage portion in addition to the first cylindrical portion for passing the elongate member (such as a wire harness) therethrough, and this tubular passage portion extends outwardly from the outer peripheral surface of the connecting portion interconnecting the first and second cylindrical portions. Therefore, an additional elongate member, such as a cable and a hose, can be passed through this passage portion. And besides, the passage portion is in the form of an independent tubular portion, and the axis of the passage portion extends along a generatrix of the outer periphery of the first cylindrical portion. Therefore, when the second cylindrical portion is reversed or turned inside out to be fitted over the first cylindrical portion, the second cylindrical portion will not interfere with the passage portion and the cable or the like, passing through this passage portion, and therefore the second cylindrical portion can be positively reversed. The passage portion is in the form of an independent tubular portion, and therefore in the reversed condition of the second cylindrical portion, the cable or the like can be passed through the passage portion from the rear side.
In the present invention, a plurality of guide portions project radially outwardly from the outer peripheral surface of the first cylindrical portion with respect to an axis of the first cylindrical portion, and can contact the peripheral edge of the mounting hole in an inscribed manner, and one of the guide portions is formed on an outer peripheral surface of the passage portion, and extends along this passage portion.
The grommet of this construction has the guide portions which can contact the peripheral edge of the mounting hole in an inscribed manner, and therefore when the end portion of the grommet is inserted into the mounting hole while guiding the grommet by the guide portions, the first cylindrical portion can be inserted into the mounting hole in such a manner that the first cylindrical portion is automatically brought into alignment with the mounting hole. In this case, one of the guide portions is formed on the outer peripheral surface of the passage portion, and extends therealong, and therefore the passage portion is reinforced. And besides, since the guide portion and the passage portion do not need to be provided separately from each other, the arrangement of the two can be easily effected.